The trades tell us:
... Thanks to Warner Bros. Animation, “Elf: Buddy’s Musical Christmas,” a one-hour special that airs Dec. 16 on NBC at 8 p.m., with Jim Parsons voicing the titular character originated by Ferrell in the 2003 pic.
Animation house Screen Novelties, which specializes in stop motion, created the TV version. “Warners thought doing it in stop motion would be cool, given the art’s historical ties with Christmas specials,” said co-founder Seamus Walsh (above, center).
The studio also may have been swayed by the success of 2012’s “A SpongeBob Christmas Special,” which Screen Novelties created for Nickelodeon. ...
Stop motion will never die, so long as their are television Christmas specials (and Henry Selick).